Impact of probiotic on anxiety and depression symptoms in pregnant and lactating women and microbiota of infants: A systematic review and meta-analysis

Background Probiotics are non-invasive therapies composed of live bacteria and yeast. Administration of prebiotics improved the health status of pregnant and lactating women, as well as newborns. This review aimed to appraise the evidence concerning the effectiveness of probiotics on the mental health of pregnant women, lactating mother and the microbiota of the newborn. Methods This systematic review and meta-analysis ascertained quantitative studies published in Medline (PubMed), Clinical Key, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Cochrane Library, and Google scholar. Two authors independently screened and extracted the data from the primary studies that analysed the efficacy of probiotics on the mental health of pregnant and lactating women and the microbiota of the newborn. We adopted Cochrane Collaboration guidelines and reported using the Preferred Reporting Items for Systematic review and Meta-Analysis (PRISMA) statement. The qualities of included trials were assessed by Cochrane collaboration's risk of bias tool (ROB-2). Results Sixteen trials comprised 946 pregnant women, 524 were lactating mothers, and 1678 were infants. The sample size of primary studies ranged from 36 to 433. Probiotics were administered as interventions, using either a single strain of Bifidobacterium or Lactobacillus or a double-strain combination of Lactobacillus and Bifidobacterium. Probiotics supplementation reduced anxiety in pregnant (n = 676, standardised mean difference (SMD) = 0.01; 95% confidence interval (CI) = -0.28,0.30, P = 0.04, I2 = 70) and lactating women (n = 514, SMD = -0.17; 95% CI = -1.62,1.27, P = 0.98, I2 = 0). Similarly, probiotics decreased depression in pregnant (n = 298, SMD = 0.05; 95% CI = -0.24,0.35, P = 0.20, I2 = 40) and lactating women (n = 518, SMD = -0.10; 95% CI = -1.29,-1.05, P = 0.11, I2 = 60%). Similarly, probiotics supplementation improved the gut microbiota and reduced the duration of crying, abdominal distension, abdominal colic and diarrhoea. Conclusion Non-invasive probiotic therapies are more useful to pregnant and lactating women and newborns. Registration The review protocol was registered with PROSPERO (CRD42022372126).

Impact of probiotic on anxiety and depression symptoms in pregnant and lactating women and microbiota of infants: A systematic review and meta-analysis Probiotics consist of live bacteria and yeast that offer a range of health benefits. Probiotics enhance the gut microbiota and immunity and reduce inflammation and allergic reactions [3]. The gut microbiota is closely related to the central nervous system. Probiotics not only restore normal functions of the digestive system, but they also strengthen functions of other organs such as the nervous system, pituitary function and endocrine system [4].
The prevalence of anxiety, depression, and psychological upset is common in pregnant, perinatal, and postnatal women. However, mental health is the major contributing factor to low birth weight and preterm delivery. Therefore, balancing diet and a safe environment is important for pregnant and lactating women [5][6][7].
Antenatal nutrition and gestational age are important factors for establishing infant microbiota. In addition, several contributing factors altered the infant gut microbiota, such as preterm delivery, supplementary feeding use of drugs and dietary pattern [8][9][10][11][12][13]. Probiotic supplementation is a non-pharmacological, non-invasive treatment that benefits both nursing mothers and newborns. Results from an earlier study showed that probiotic supplements significantly reduced infant's regurgitation, duration of cry and abdominal colic [14][15][16].
However, only a few systematic reviews and meta-analyses were conducted to evaluate probiotics' effect on depression symptoms in adults [17,18], prenatal women [19] and perinatal and postnatal mothers. In addition, pooled the data from previous reviews unclear and retrieved from both randomized control trials (RCTs) and quasi-experimental studies. Therefore, this systematic review and meta-analysis aimed to evaluate the effectiveness of probiotics on mental health and microbiota of newborns.

METHODS
The review has adopted Cochrane guidelines and reported using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) [20]. The protocol has been registered with PROSPERO CRD42022372126.
A comprehensive search was conducted using a combination of MeSH terms or keywords connected to the PICO format. The search strategy was carried out using the following keywords: Antenatal women, parity, gravid, pregnant women, perinatal women, intra-natal, postnatal women, lactation mother, breastfeeding mother, neonates, newborn, infants, Lactobacillus acidophilus, probiotics, probiotic supplementation, microbiota, depression, mental health, anxiety, and afraid. Two authors (KH, AS) independently searched the online databases, namely MEDLINE (PubMed), Cumulative Index to Nursing and Allied Health Literature (CINAHL), EMBASE, Web of Science, SCOPUS, and Clinical Key, for RCTs published in the English language from January 2012 to October 2022. The included articles were screened, and duplicate articles were excluded based on review criteria. The reference tracking of relevant articles was manually searched for additional studies.
During the first stage of the search, a total of 18 300 items were identified, and eight studies from citation search with 1309 of them being removed before screening. The remaining studies' methodology and abstract were screened. A total of 16 991 records, and 16 967 articles and eight citation search articles were excluded as they did not meet the review criteria. Further, we removed six articles due to the unavailability of the full text. Finally, 16 RCTs were included after fulfilling the review criteria: probiotic was the principle intervention for all primary studies published between 2012 and 2022 in the English language. Anxiety and depressions of pregnant and lactating women, as well as neonatal microbiota, were primary outcomes. The reasons for exclusion of primary studies were: probiotics combined with other supplementation and / or not evaluated depression and anxiety, difference in the primary outcome. The flow diagram of the study selection process is depicted in Figure 1. The Cochrane risk of bias tool-2 [21] was employed to assess the quality of the included RCTs. The details regarding the percentages across the included trials and judgments about each risk of bias item is depicted in Figure 2.
Two independent reviewers (KH) extracted the data from the primary studies, and any discrepancies in the initial judgments were confirmed by a third reviewer (LT). The data extraction form included the author's name, title, year of publication, country, study purpose, sample size, study design, analysis method, risk of bias, and major findings reported by the author(s).

Statistics analysis
The meta-analysis was performed to examine the effects of probiotic supplementation among pregnant women, lactating mothers, and newborns. Anxiety, depression, and neonatal microbiota were the primary outcomes of the included studies evaluated between the probiotic and placebo groups. The effects of the probiotic intervention were calculated using a random-effects model to compute weighted and standardized mean differences with confidence intervals (CIs) of 95%. The heterogeneity of the included trials was analysed and classified as mild >50%, moderate 50%-75%, and high >75% using the I 2 value.

RESULTS
The pooled data of primary studies summarized under the following headings: authors name, year of publication, study design, sample size, type of intervention, and major findings ( Table 1).

Probiotics administered in lactating mother and newborn
Three studies (n = 524) assessed the effectiveness of probiotics among lactating women and their newborns [26,27,34]. The following probiotics combinations used as interventions such as 9 X 10 11 of VSL, L. acidophilus, L. plantarum, L. paracase, L. debrueckii and bulgaricus B. infantis & S. thermophilus [26] 5 X 10 9 L.GG, 5 X 10 9 CFU L. rhanmosus LC705, 2 x 10 8 CFU P freudenreidii ssp, shermani JS [27] and 5 × 10 6 actiregulari [34]. Compared to the control group intervention group increases lactobacilli and bifidobacteria in colostrum and mature breast milk [26] improves gut microbiota [27] and reduces the duration of cry [34] ( Table  1). Probiotics lower the risk of anxiety and depression in pregnant and lactating women.  There was a substantial difference between the two groups, with anxiety and depression being much lower in the probiotics group than in the placebo group. Probiotic therapy was found to be an effective treatment for anxiety and depression in pregnant and lactation women.

Meta-analysis
Only four primary studies reported numerical data on mental health among pregnant and lactating women. Therefore, we selected these trials for the meta-analysis.

DISCUSSION
This systematic review and meta-analysis evaluated the efficiency of probiotic supplementations for pregnant and lactating women and infant's microbiota. Supplementation of probiotics in pregnant women has improved mental health [19,39]. There is strong evidence that probiotics benefit the gut and nervous systems, known as the "gut-brain axis" [40,41]. The role of probiotics in alleviating mood and cognition problems is still controversial. Several pieces of evidence support the claim that probiotics benefit both gut and brain health. In addition, recent studies have proved that there is a strong link between the digestive system and the nervous system [42].
Lactobacillus and Bifidobacterium are probiotic bacteria that have been shown to improve immune system function, respond to the formation of short-chain fatty acids, reduce inflammation, and boost gastric emptying through the action of mucosal receptors [43].
The main strength of our review is that we included double-blinded, randomized control trials. We also summarized the dosage, strain, and species of probiotics. Our systematic review and meta-analysis revealed that probiotic supplementation is a non-invasive therapy that can be used routinely in prenatal and postnatal women and newborns to improve the physical and mental well-being and microbiota of newborns [53]. Probiotics, prebiotics and synbiotics supplementation reduced prenatal depression [54], newborn abdominal colic [45,55] and regurgitation [55].

REFERENCES
Various biomarkers and genetic methods are used to create distinct probiotic strains and species to increase neonatal gut microbiota colonisation. As a result, more randomized control trials are needed to investigate the specific probiotic strains used to understand the effects on pregnancy, lactating mothers, and newborns.
There were significant limitations; some studies included C-sections and vaginal births. Original studies did not report numerical data on primary outcomes, especially neonates' microbiota. Lastly, anxiety and depression decreased in the probiotics group, but the primary studies were unclear about other extraneous variables that may affect mental health in pregnant and lactating women.

CONCLUSION
Non-invasive therapies, such as probiotics, are more useful to pregnant and breastfeeding women and newborns. Administration of probiotics enhanced the gut microbiota, particularly newborns. The microbiome promotes gut colonization in newborns, influencing digestion and nutrition absorption. Henceforth this study provides strong evidence of the importance of probiotics for prenatal, postnatal, and newborn health.